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Hopeite

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Hopeite
Hopeite Belgium – Type locality
General
CategoryPhosphate minerals
Formula
(repeating unit)
Zn3(PO4)2·4H2O
IMA symbolHop[1]
Strunz classification8.CA.30
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnma
Identification
Formula mass458.17 g/mol
ColorColorless, gray white, yellow, white, light yellow
Crystal habitEncrustations – Forms crust-like aggregates on matrix. Prismatic – crystals shaped like slender prisms (e.g. tourmaline). Reniform – kidney-like in shape (e.g. hematite).
Cleavage[100] Perfect, [010] good, [001] poor
FractureUneven – flat surfaces (not cleavage) fractured in an uneven pattern
Mohs scale hardness3–3.5
LusterVitreous (glassy)
StreakWhite
Specific gravity3
Optical propertiesBiaxial (−), a = 1.572–1.574, b = 1.582–1.591, g = 1.59–1.592
Other characteristicsNon-radioactive, non-magnetic

Hopeite is a hydrated zinc phosphate with formula: Zn3(PO4)2·4H2O. It is a rare mineral used mainly as a collectors specimen.

Hopeite crystallizes in the orthorhombic system with prismatic, vitreous white to yellow crystals. It also forms druzy encrustations and reniform (kidney-shaped) masses. The related mineral parahopeite, which has the same composition but different crystal structure, is triclinic. The minerals are formed through oxidation of sphalerite by the presence of phosphate-rich solutions.

It was first described in 1822 from Moresnet, Liège Province, Belgium and is named after Scottish chemist, Thomas Charles Hope (1766–1844) of the University of Edinburgh.

It has been found in Zambia associated with lazulite.

Hopeite is one of the two conversion minerals arising from the application of the rust converter 'Fertan'.[2]

References

[edit]
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Fertan Rust Destroyer from Autorepaired". Archived from the original on 2017-10-21. Retrieved 2022-04-15.
Orange-brown hopeite prisms to 3 mm on a nearly solid matrix of glassy, pastel yellow-green parahopeite crystals. Locality: Kabwe Mine (Broken Hill Mine), Kabwe, Central Province, Zambia. Broken Hill is the type locality for parahopeite.